net: change illegal_highdma to use dma_mask

Robert Hancock pointed out two problems about NETIF_F_HIGHDMA:

-Many drivers only set the flag when they detect they can use 64-bit DMA,
since otherwise they could receive DMA addresses that they can't handle
(which on platforms without IOMMU/SWIOTLB support is fatal). This means that if
64-bit support isn't available, even buffers located below 4GB will get copied
unnecessarily.

-Some drivers set the flag even though they can't actually handle 64-bit DMA,
which would mean that on platforms without IOMMU/SWIOTLB they would get a DMA
mapping error if the memory they received happened to be located above 4GB.

http://lkml.org/lkml/2010/3/3/530

We can use the dma_mask if we need bouncing or not here. Then we can
safely fix drivers that misuse NETIF_F_HIGHDMA.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/dev.c b/net/core/dev.c
index 427cd53c118dfafc48ef34074e981c3b4343b21f..e19cdae49fefe3dcc20813bd7d120ef7b5970fd4 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -129,6 +129,7 @@
 #include <linux/jhash.h>
 #include <linux/random.h>
 #include <trace/events/napi.h>
+#include <linux/pci.h>
 
 #include "net-sysfs.h"
 
@@ -1804,14 +1805,21 @@ static inline int illegal_highdma(struct net_device *dev, struct sk_buff *skb)
 {
 #ifdef CONFIG_HIGHMEM
        int i;
+       if (!(dev->features & NETIF_F_HIGHDMA)) {
+               for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+                       if (PageHighMem(skb_shinfo(skb)->frags[i].page))
+                               return 1;
+       }
 
-       if (dev->features & NETIF_F_HIGHDMA)
-               return 0;
-
-       for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
-               if (PageHighMem(skb_shinfo(skb)->frags[i].page))
-                       return 1;
+       if (PCI_DMA_BUS_IS_PHYS) {
+               struct device *pdev = dev->dev.parent;
 
+               for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+                       dma_addr_t addr = page_to_phys(skb_shinfo(skb)->frags[i].page);
+                       if (!pdev->dma_mask || addr + PAGE_SIZE - 1 > *pdev->dma_mask)
+                               return 1;
+               }
+       }
 #endif
        return 0;
 }